"Ho-Ren (Jack) Chuang" <horen.chuang@xxxxxxxxx> writes: > The current memory tier initialization process is distributed across > two different functions, memory_tier_init() and memory_tier_late_init(). > This design is hard to maintain. Thus, this patch is proposed to reduce > the possible code paths by consolidating different > initialization patches into one. > > The earlier discussion with Jonathan and Ying is listed here: > https://lore.kernel.org/lkml/20240405150244.00004b49@xxxxxxxxxx/ > > If we want to put these two initializations together, they must be > placed together in the later function. Because only at that time, > the HMAT information will be ready, adist between nodes can be > calculated, and memory tiering can be established based on the adist. > So we position the initialization at memory_tier_init() to the > memory_tier_late_init() call. Moreover, it's natural to keep > memory_tier initialization in drivers at device_initcall() level. > > If we simply move the set_node_memory_tier() from memory_tier_init() > to late_initcall(), it will result in HMAT not registering > the mt_adistance_algorithm callback function, because > set_node_memory_tier() is not performed during the memory tiering > initialization phase, leading to a lack of correct default_dram > information. > > Therefore, we introduced a nodemask to pass the information of the > default DRAM nodes. The reason for not choosing to reuse > default_dram_type->nodes is that it is not clean enough. So in the end, > we use a __initdata variable, which is a variable that is released once > initialization is complete, including both CPU and memory nodes for HMAT > to iterate through. > > This patchset is based on commits <cf93be18fa1b> ("memory tier: create > CPUless memory tiers after obtaining HMAT info") and > <a72a30af550c> ("memory tier: dax/kmem: introduce an abstract layer for > finding, allocating, and putting memory types"): > [0/2] https://lkml.kernel.org/r/20240405000707.2670063-1-horenchuang@xxxxxxxxxxxxx > [1/2] https://lkml.kernel.org/r/20240405000707.2670063-2-horenchuang@xxxxxxxxxxxxx > [1/2] https://lkml.kernel.org/r/20240405000707.2670063-3-horenchuang@xxxxxxxxxxxxx > > Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@xxxxxxxxxxxxx> > Suggested-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> LGTM, Thanks! Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx> > --- > - v3: > * Combine the cover letter and the patch. > * Remove extern default_dram_type > * Remove __initdata in a extern variable > * Roll back coding style, fix comment description > - v2: > Thanks to Huang, Ying's and Andrew's comments > * Add a cover letter > * Add Suggested-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> > * Add get/put_online_mems() protection in memory_tier_late_init() > * If memtype is set, skip initializing its node > * Remove redundant code/comments or rewrite code in a cleaner manner > * https://lore.kernel.org/all/20240628060925.303309-1-horen.chuang@xxxxxxxxx/ > - v1: > * https://lore.kernel.org/all/20240621044833.3953055-1-horen.chuang@xxxxxxxxx/ > > - Open to discussion: > * Should we use `continue` or `break` if set_node_memory_tier() fails in > memory_tier_late_init()? I've changed it to `continue` in v3. > * Compute the default_dram_nodes mask in hmat when needed? Currently, > it still remains in memory-tiers.c > * Instead of using guard(mutex)(), use mutex_lock() as it was to make a > cleaner diff? > > Thanks, > Ho-Ren (Jack) Chuang > > drivers/acpi/numa/hmat.c | 5 +--- > include/linux/memory-tiers.h | 2 ++ > mm/memory-tiers.c | 54 ++++++++++++++---------------------- > 3 files changed, 24 insertions(+), 37 deletions(-) > > diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c > index 2c8ccc91ebe6..a2f9e7a4b479 100644 > --- a/drivers/acpi/numa/hmat.c > +++ b/drivers/acpi/numa/hmat.c > @@ -940,10 +940,7 @@ static int hmat_set_default_dram_perf(void) > struct memory_target *target; > struct access_coordinate *attrs; > > - if (!default_dram_type) > - return -EIO; > - > - for_each_node_mask(nid, default_dram_type->nodes) { > + for_each_node_mask(nid, default_dram_nodes) { > pxm = node_to_pxm(nid); > target = find_mem_target(pxm); > if (!target) > diff --git a/include/linux/memory-tiers.h b/include/linux/memory-tiers.h > index 0d70788558f4..0dc0cf2863e2 100644 > --- a/include/linux/memory-tiers.h > +++ b/include/linux/memory-tiers.h > @@ -38,6 +38,7 @@ struct access_coordinate; > #ifdef CONFIG_NUMA > extern bool numa_demotion_enabled; > extern struct memory_dev_type *default_dram_type; > +extern nodemask_t default_dram_nodes; > struct memory_dev_type *alloc_memory_type(int adistance); > void put_memory_type(struct memory_dev_type *memtype); > void init_node_memory_type(int node, struct memory_dev_type *default_type); > @@ -76,6 +77,7 @@ static inline bool node_is_toptier(int node) > > #define numa_demotion_enabled false > #define default_dram_type NULL > +#define default_dram_nodes NODE_MASK_NONE > /* > * CONFIG_NUMA implementation returns non NULL error. > */ > diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c > index 6632102bd5c9..4775b3a3dabe 100644 > --- a/mm/memory-tiers.c > +++ b/mm/memory-tiers.c > @@ -43,6 +43,7 @@ static LIST_HEAD(memory_tiers); > static LIST_HEAD(default_memory_types); > static struct node_memory_type_map node_memory_types[MAX_NUMNODES]; > struct memory_dev_type *default_dram_type; > +nodemask_t default_dram_nodes __initdata = NODE_MASK_NONE; > > static const struct bus_type memory_tier_subsys = { > .name = "memory_tiering", > @@ -671,28 +672,35 @@ EXPORT_SYMBOL_GPL(mt_put_memory_types); > > /* > * This is invoked via `late_initcall()` to initialize memory tiers for > - * CPU-less memory nodes after driver initialization, which is > - * expected to provide `adistance` algorithms. > + * memory nodes, both with and without CPUs. After the initialization of > + * firmware and devices, adistance algorithms are expected to be provided. > */ > static int __init memory_tier_late_init(void) > { > int nid; > + struct memory_tier *memtier; > > + get_online_mems(); > guard(mutex)(&memory_tier_lock); > + > + /* Assign each uninitialized N_MEMORY node to a memory tier. */ > for_each_node_state(nid, N_MEMORY) { > /* > - * Some device drivers may have initialized memory tiers > - * between `memory_tier_init()` and `memory_tier_late_init()`, > - * potentially bringing online memory nodes and > - * configuring memory tiers. Exclude them here. > + * Some device drivers may have initialized > + * memory tiers, potentially bringing memory nodes > + * online and configuring memory tiers. > + * Exclude them here. > */ > if (node_memory_types[nid].memtype) > continue; > > - set_node_memory_tier(nid); > + memtier = set_node_memory_tier(nid); > + if (IS_ERR(memtier)) > + continue; > } > > establish_demotion_targets(); > + put_online_mems(); > > return 0; > } > @@ -875,8 +883,7 @@ static int __meminit memtier_hotplug_callback(struct notifier_block *self, > > static int __init memory_tier_init(void) > { > - int ret, node; > - struct memory_tier *memtier; > + int ret; > > ret = subsys_virtual_register(&memory_tier_subsys, NULL); > if (ret) > @@ -887,7 +894,8 @@ static int __init memory_tier_init(void) > GFP_KERNEL); > WARN_ON(!node_demotion); > #endif > - mutex_lock(&memory_tier_lock); > + > + guard(mutex)(&memory_tier_lock); > /* > * For now we can have 4 faster memory tiers with smaller adistance > * than default DRAM tier. > @@ -897,29 +905,9 @@ static int __init memory_tier_init(void) > if (IS_ERR(default_dram_type)) > panic("%s() failed to allocate default DRAM tier\n", __func__); > > - /* > - * Look at all the existing N_MEMORY nodes and add them to > - * default memory tier or to a tier if we already have memory > - * types assigned. > - */ > - for_each_node_state(node, N_MEMORY) { > - if (!node_state(node, N_CPU)) > - /* > - * Defer memory tier initialization on > - * CPUless numa nodes. These will be initialized > - * after firmware and devices are initialized. > - */ > - continue; > - > - memtier = set_node_memory_tier(node); > - if (IS_ERR(memtier)) > - /* > - * Continue with memtiers we are able to setup > - */ > - break; > - } > - establish_demotion_targets(); > - mutex_unlock(&memory_tier_lock); > + /* Record nodes with memory and CPU to set default DRAM performance. */ > + nodes_and(default_dram_nodes, node_states[N_MEMORY], > + node_states[N_CPU]); > > hotplug_memory_notifier(memtier_hotplug_callback, MEMTIER_HOTPLUG_PRI); > return 0;
